Problem: What do the following two equations represent? $-3x+3y = 1$ $-15x+15y = 5$
Solution: Putting the first equation in $y = mx + b$ form gives: $-3x+3y = 1$ $3y = 3x+1$ $y = 1x + \dfrac{1}{3}$ Putting the second equation in $y = mx + b$ form gives: $-15x+15y = 5$ $15y = 15x+5$ $y = 1x + \dfrac{1}{3}$ The above equations turn into the same equation, so they represent equal lines.